Rear Firewall Question

NHRA requires a rear firewall (including package tray) made of 0.024" steel or 0.032" aluminum if the battery or fuel cell is in the trunk. My question is, instead of making a one-piece sheet metal panel covering the whole package tray, can one simply cover the speaker holes.

I was thinking of making some covers for the speaker holes out of 0.032" aluminum attached with either rivets or sheet metal screws. Then I'd like to make a full size package tray out of fiber board covered in carpet to match my door panels. Would that be NHRA legal?? Have any of you guys done something similar?